using accumarray to combine text

Hi,

I am trying to use accumarray to concatenate string.

tdata = table([ 1 2 2 3 4 2]', ["a","b","c","d","e","f"]', 'VariableNames',{'EBID','Name'});
[uniqEBID,~,JGrp] = unique( tdata(:, {'EBID'}));
joinStr = @(tStr) { sprintf([repmat('%s|| ', 1, length( tStr)-1) '%s'], string( tStr))};
joinStr( tdata.Name) % anonymous function seems to do the job

However when running script below, i got error message

accumarray( JGrp,  tdata.Name, [], joinStr)

Error using accumarray

Second input VAL must be a full numeric, logical, or char vector or scalar.

[Pete sherer]

the answer should be

"a"

"b|| c|| f"

"d"

"e"

Answer 1

[Stephen23]

T = table([1;2;2;3;4;2], ["a";"b";"c";"d";"e";"f"], 'VariableNames',{'EBID','Name'})

T = 6×2 table
    EBID    Name
    ____    ____

     1      "a" 
     2      "b" 
     2      "c" 
     3      "d" 
     4      "e" 
     2      "f" 

G = findgroups(T.EBID);
F = @(s)join(s,"||");
S = splitapply(F,T.Name,G)

S = 4×1 string array
    "a"
    "b||c||f"
    "d"
    "e"

Answer 2

[Voss]

Does this do what you want?

tdata = table([ 1 2 2 3 4 2]', ["a","b","c","d","e","f"]', 'VariableNames',{'EBID','Name'});
[uniqEBID,~,JGrp] = unique( tdata(:, {'EBID'}));
joinStr = @(tStr) { sprintf([repmat('%s|| ', 1, length( tStr)-1) '%s'], string( tStr))};
% joinStr( tdata.Name) % anonymous function seems to do the job
joinStr( tdata.Name(JGrp))

ans = 1×1 cell array
    {'a|| b|| b|| c|| d|| b'}